 /*******************************************************************************
  * Copyright (c) 2000, 2003 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Common Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/cpl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.ui.internal.contexts;

 import java.util.ArrayList ;
 import java.util.Collections ;
 import java.util.List ;

 abstract class AbstractContextRegistry implements IContextRegistry {
     protected List contextContextBindingDefinitions = Collections.EMPTY_LIST;
     protected List contextDefinitions = Collections.EMPTY_LIST;
     private ContextRegistryEvent contextRegistryEvent;
     private List contextRegistryListeners;

     protected AbstractContextRegistry() {
     }

     public void addContextRegistryListener(IContextRegistryListener contextRegistryListener) {
         if (contextRegistryListener == null)
             throw new NullPointerException ();

         if (contextRegistryListeners == null)
             contextRegistryListeners = new ArrayList ();

         if (!contextRegistryListeners.contains(contextRegistryListener))
             contextRegistryListeners.add(contextRegistryListener);
     }

     protected void fireContextRegistryChanged() {
         if (contextRegistryListeners != null) {
             for (int i = 0; i < contextRegistryListeners.size(); i++) {
                 if (contextRegistryEvent == null)
                     contextRegistryEvent = new ContextRegistryEvent(this);

                 (
                     (IContextRegistryListener) contextRegistryListeners.get(
                         i)).contextRegistryChanged(
                     contextRegistryEvent);
             }
         }
     }

     public List getContextContextBindingDefinitions() {
         return contextContextBindingDefinitions;
     }

     public List getContextDefinitions() {
         return contextDefinitions;
     }

     public void removeContextRegistryListener(IContextRegistryListener contextRegistryListener) {
         if (contextRegistryListener == null)
             throw new NullPointerException ();

         if (contextRegistryListeners != null)
             contextRegistryListeners.remove(contextRegistryListener);
     }
 }

